"The depth of a soft tissue mass does not appear to be linked to the probability of malignancy," UK researchers say [1]. This key finding "is not supportive of the current guidelines on assessment of soft tissue tumours," they added.
Researchers looked at the MRI findings of 571 consecutive patients, aged from two to 92 years, referred to a supra-regional orthopaedic oncology unit with a suspected soft-tissue neoplasm. They reported that 480 of the lesions were deep. On histology, 288 lesions were malignant neoplastic, 197 benign neoplastic and 86 non-neoplastic.
There was no significant relationship between lesion depth and a malignant diagnosis. A significant relationship was identified between lesion size and diagnosis; however, the authors noted that 65 per cent of benign tumours were 5cm in diameter or more and ten per cent of malignant lesions were less than 5cm.
The NICE guidelines for referral of suspected cancer, released in 2005, advised that referral for suspicion of soft tissue sarcoma should be made if a palpable lump is greater than 5cm in diameter, deep to the fascia, painful or increasing in size, or if it is a recurrence after previous excision.
The authors said: "It is important that when the probability of malignancy is being considered, a superficial relationship to the fascia and a lesion size less than 5cm should not be taken to exclude the possibility of soft-tissue sarcoma."
Dr Steven James, consultant radiologist at Royal National Orthopaedic Hospital Stanmore, UK and one of the study authors, emphasized that the findings were most relevant to tertiary care. He said the guidelines are still useful but added: "The study acts as a note of caution."
In an accompanying commentary, Dr Charles Wakely of United Bristol Healthcare NHS trust, in Bristol, UK, said the study "reminds us all of the difficulties in distinguishing between benign and malignant lesions.... It is clear that new approaches are necessary."
But Dr David Wilson, a consultant radiologist at the Nuffield Orthopaedic Centre NHS Trust in Oxford, UK, reiterated that the paper's scope included only those patients referred to a tertiary centre, thereby excluding numerous superficial benign lesions. He said the guidelines are applicable to general practice and warned that these findings "cannot be used to influence general orthopedic practice."
[1] 'MRI of soft-tissue masses: the relationship between lesion size, depth, and diagnosis'. Clinical Radiology, Volume 63, Issue 4, April 2008.
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